Wednesday, February 28, 2007

Tests on skeletons from Europeans who lived around 5000 BC show they all shared the genetic trait we call "lactose intolerance," which meant that adults who drank milk would suffer bloating and diarrhea.

But suddenly, that all changed. With the arrival of dairy herds, the gene that lets some adults digest milk became the single greatest key to survival all across Europe, a new study says.

Today, more than 90 per cent of northern Europeans can digest milk as adults. That's a complete rewriting of the genetic blueprint carried by Neolithic peoples of 5000 BC.

The gene that produces lactase was probably a minor little mutation that popped up occasionally in small numbers all along, says genetics expert Earl Brown of the University of Ottawa.

"It would be like the one extra blade on your Swiss Army knife that you never use. It's just hanging on your belt," he said. "Then suddenly you need it. And anyone who has that blade has a big evolutionary advantage."

You’re right in noticing a slow down in postings. Acute tendonitis is limiting my time at the keyboard and that has to be spent on ‘real' work. Things will normalize when they do….

Ecologists continue to debate how different species manage to coexist. If two species use identical resources, such as food, invariably one will be more efficient and out-compete the other. The classical explanation is that each species has evolved morphological or physiological traits that allow it to exploit some resources more efficiently than all other species.

Such partitioning of resources essentially provides each species with exclusive access to resources necessary for its survival. Although coexistence is often attributed to interspecific differences in morphology, direct evidence is relatively rare.

Dabbling ducks, which include the ubiquitous mallard, are a good example. Dabbling ducks are primarily filter-feeders. They use lamellae, which are comb-like projections on the bill, to sieve food particles from pond water. Many ecologists, including Darwin, suggested that ducks coexist because interspecific differences in the spacing of bill lamellae allow each species to consume food particles of different sizes. New Research by Brent Gurd has demonstrated that interspecific differences in lamellar length, not spacing, allow ducks to partition food by size.

To test his idea, Gurd created virtual bills using computer software typically used by engineers to design complex machinery. "The software allowed me to create exact, three-dimensional replicas of duck bills complete with articulating joints" said Gurd. "The replicas allowed me to determine the particle sizes each duck could ingest and the rate at which they could ingest them."

I'm always intersted in research that helps shed light on why multiple morphologically similar species can co-exist in a small region.

Saturday, February 24, 2007

Sixteen football-sized vertebrae belonging to a prehistoric whale dating back 5 million years ago were uncovered February 22 on the estate of Castello Banfi, in Montalcino, Tuscany. According to paleontologists, it could be the oldest whale ever found in this part of Italy, an area that was once covered with as much as 82 feet of water before the sea started its slow retreat millions of years ago to it’s current location some 18 miles away.

The whale is estimated to be 33 feet long, and is completely intact with the animal’s head pointed uphill towards the castle. “The whale dates from the Pliocene era when the Mediterranean was at its biggest”, says paleontologist Simone Casati. When the excavation is complete, Casati says the skeleton will be moved to Florence.

The whale vertebrae in foreground. Photo: Monica Larner

The nearly 7,000-acre estate produces 300,000 cases of top wines such as Brunello and Supertuscans.

Abstract [edit]: A catastrophic bolide impact is widely recognized as the trigger of the mass extinction that occurred 65 million years ago at the Cretaceous-Tertiary boundary, when animals such as dinosaurs (on land) and ammonites (in the sea) became extinct.

One possible killing mechanisms involves a global collapse of food chains due to the shutdown of photosynthesis by sun-blocking dust clouds and soot from fires. It is still unclear whether the intensity of these perturbations is related to the distance from the impact site in today’s Mexico and whether it is related to paleolatitude.

The ecological composition of organisms from high southern latitudes that lived on the sea floor at that time, such as clams, snails, corals, and sea urchins, changed significantly across the boundary and in a way that was consistent with the scenario of reduced availability of food after the impact event: Animals were less abundant for some time; starvation-resistant groups and animals not relying directly on photosynthetic organisms as a food source became more dominant; individuals with larval stages that do not need to feed on phytoplankton became proportionally more common; the average body size of individuals within communities became smaller; and individuals with low metabolic rates or inactive lifestyles became better represented.

A return to pre-extinction conditions of the various ecological attributes occurred over unequal time spans, indicating that recovery from the mass extinction was uncoordinated with respect to ecological traits.

Robert Reisz is being honoured for more than 35 years of research excellence by joining the ranks of the American Association for the Advancement of Science (AAAS). The society inducted him as a fellow during its annual conference held last week.

"I am humbled that they chose me, and I think it was because my research has had an impact in my field," says Reisz, a paleontologist at the University of Toronto. "I like to look at the very beginnings of major evolutionary events – to that time when mammals and reptiles and birds were just becoming separate from each other. It was an exciting time in history, about 270 million years ago – it was between ice ages, just like the time we are living in now – and I think my work has led to a greater understanding of what happened then."

Reisz earned three degrees in zoology at McGill University during the 1960s and 1970s, culminating in a doctorate in 1975. After spending a year at UCLA, he began research at the University of Toronto where he remains.

Thursday, February 22, 2007

From Jeanna Bryner at LiveScience.com comes an article on Elizabeth Brainerd, Stephen Gatesy and David Baier on their use of new 3-D video techniques to study the skeletons of animals on the move.

Scientists are filming alligators as they trot along treadmills and pigeons on the fly in wind tunnels. But rather than a view of flesh and muscles, a “This will be like having X-ray vision—you'll be able to see through skin and muscle and watch a skeleton move in 3-D," said lead scientist Elizabeth Brainerd of Brown University. “Imagine animated X-ray movies of flying bats or flexing knees."

Speaking of Steve reminds me of this photo I've had kicking around for a while. Taken at the end of the 1985 field season in DPP, this motley crew includes Steve Gatesy (center, back row with the unruly head of hair), me beside him, Don Brinkman from the RTMP (keeling, far right, 2nd row), and Per Ahlberg on the ground in front. Where are they all now I wonder?

The ancient humans are thought to have died out in most parts of Europe by about 35,000 years ago. Now new data from their last known refuge in southern Iberia indicates the final population was probably beaten by a cold spell some 24,000 years ago.

Sediment cores drilled from the sea bed near the Balearic Islands show the average sea-surface temperature plunged to 8C. Modern-day sea surface temperatures in the same region vary from 14C to 20C.

Gorham's Cave on Gibraltar shows evidence of occupation by groups of Neanderthals until 24,000 years ago. But thereafter, researchers have found no signs of their presence.

To investigate the stability of ancient cave bear populations over time, the researchers studied mitochondrial DNA sequence from 29 cave bear teeth from three geographically close caves in the Ach Valley, near the Danube River in modern-day southern Germany.

The findings indicated that while four sequence types (known as haplotypes) corresponded to bears 28,000 to 38,000 years old, a fifth DNA haplotype was found only in bears that were 28,000 years old or younger. These data suggested that what had been a stable, long-established cave bear population became disrupted around 28,000 years ago and was replaced by a new, genetically distinct cave bear group.

The timing of the disruption appears to roughly coincide with the arrival of modern humans in the Ach Valley, thought to have occurred by 32,000 years ago. The researchers suggest that human influence in the form of hunting and competition for sheltering caves may represent a plausible explanation for the disruption in the cave bear population.image

Phylogenetic tree of 26 published cave bear haplotypes and temporal relationship of the two haplogroups in the Ach Valley.

(A) Phylogenetic positions of the sequences from two reproductively isolated cave bear populations from Austria (dotted arrows) and from the Ach Valley (normal arrows). Haplotypes from the older sequence group from the Ach Valley fall within the same clade as those from the higher elevation site (2,000 m) in Austria (blue arrows), while the younger haplotype from the Ach Valley clusters with haplotypes from the lower elevation site (1,300 m above sea level) in Austria (red arrows). (B) Radiocarbon dates for the fossil teeth from the Ach Valley. The different sequence groups are shown in the same colors as in (A).

Monday, February 19, 2007

Hedin was a Swedish explorer and geographer, born in Stockholm, who led four multi-year expeditions into Central Asia between 1897 and 1935. Although not as well known as Roy Chapman Andrews his work in the regions revealed a wealth of cultural, archaeological and palaeontological wonders.

During his first major Asian expedition, he crossed the Pamirs, charted Lop Nor (Lake) in China, and finally arrived at Beijing. He then journeyed to Tibet by way of Mongolia, Siberia, and the Gobi Desert. Hedin explored Tibet and Xinjiang (Sinkiang), identified the sources of the Brahmaputra, Indus, and Sutlej rivers, and, in 1906, explored and named the Trans-Himalayas. In 1927 Hedin led an expedition of Chinese and Swedish scientists into Central Asia.

Murchison was a Scottish geologist who first differentiated the Silurian strata in the geologic sequence of Early Paleozoic strata (408-540 million years old). He believed in fossils as primary criteria. In 1831, he began researching the previously geologically unknown graywacke rocks of the Lower Paleozoic, found underlying the Old Red Sandstone in parts of Wales, which culminated in his major work the Silurian System (1839).

Murchison named the Silurian after an ancient British tribe that inhabited South Wales. He established the Devonian working with Adam Sedgwick (1839). He named the Permian (1841) after the Perm province in Russia where he made a geological survey in 1840-45.link

Matthew was a superb mammalian paleontologist and important biogeographic theorist, and also G. G. Simpson's primary mentor. Matthew published voluminiously on the fossil record of mammals and advocated a fully modern approach to taxonomy that emphasized tying scientific names to natural biological populations. His 1930 paper gives a clear statement of this position.

Matthew's key biogeographic theory was that waves of faunal migration repeatedly went from the northern continents southwards. This theory, which had obvious racial and political overtones, was justified by a "stabilist" view of paleogeography (i.e., that the continents had never moved from their modern positions), and by evidence from the relatively young fossil record of mammals, at the expense of other data that would have shown the more ancient interconnections among South America, Africa, India, and Australia. Remarkably, Matthew remained a Darwinian despite working for the autocratic orthogeneticist H. F. Osborn for three decades.

Sunday, February 18, 2007

If you’re in the Rockford/Chicago area this weekend why not take in the final day of Paleofest at the Burpee Museum? Guests include folks like Karen Chin, Tom Williamson, Peter Larson of ‘Sue’ fame, and Thomas Carr.

Haeckel was a German zoologist and evolutionist who was a strong proponent of Darwinism and proposed new notions of the evolutionary descent of man. He coined many words commonly used by biologists today, such as phylum, phylogeny, and ecology.

d'Halloy was a Belgian geologist who was an early proponent of evolution and was acknowledged by Charles Darwin in his preface to ‘On The Origin of the Species’ for his opinions on the origin of new species through descent with modification.

He determined the stratigraphy of the Carboniferous and other rocks in Belgium and the Rhine provinces, and also made detailed studies of the Tertiary deposits of the Paris Basin. link

Previously, scientists could not determine which forces contributed to regressive evolution in cave-adapted species, and many doubt the role of natural selection in this process. Darwin himself, who famously questioned the role of natural selection in eye loss in cave fishes, said, "As it is difficult to imagine that eyes, although useless, could be in any way injurious to animals living in darkness, I attribute their loss wholly to disuse."

Cave adaptations have evolved in many species independently, and each cave species can be considered a replicate of the same evolutionary experiment that asks how species change in perpetual darkness. This makes cavefish a rich source for the examination of the evolutionary process.

Their results suggest that eyes and pigmentation regressed through different mechanisms. Mutations in cave populations that affected eye or lens size invariably caused size reductions. This observation is consistent with evolution by natural selection and inconsistent with evolution by genetic drift. By contrast, mutations in cave populations that affected pigmentation sometimes caused increases instead of decreases in pigment cell density, consistent with evolution by random processes and genetic drift.

Allaying Darwin's doubts about the role of natural selection in eye loss, the researchers suggest that the high metabolic cost of maintaining the retina is the source of selection against eyes in the cave. By contrast, no such great cost is associated with pigmentation—thus, the two traits regress for different reasons.

Thursday, February 15, 2007

Image: INAH/EPAA Mexican man has discovered dozens of dinosaur footprints dating back up to 110 million years along the banks of a dried river, scientists said on Tuesday.

Biologist Oscar Polaco said more studies needed to be done to determine what species of dinosaur the fossilized prints, each one up to 60 cm across, belonged to. "At the moment we can confirm these are footprints that belong to dinosaurs that lived during the early Cretaceous," the scientist said.

Last year scientists identified 30 other dinosaur prints in the same region, an area famous for the large numbers of fossils deposited there. LINK

The migration paths taken by modern man as he colonized the world 60,000 years ago, Homo sapiens left his original home in East Africa - taking the bacterium Helicobacter pylori with him. Kyears = thousands of years. Image: Max Planck Institute for Infection Biology

When man made his way out of Africa some 60,000 years ago to populate the world, he was not alone: He was accompanied by the bacterium Helicobacter pylori, which causes gastritis in many people today. Together, man and the bacterium spread throughout the entire world.

The researchers also discovered that differences developed in the genetic makeup of the bacteria populations, just as it did in that of the various peoples of the world. This has also given scientists new insight into the paths taken by man as he journeyed across the Earth.

Tuesday, February 13, 2007

Abstract: Rate of ageing in tyrannosaurs was calculated from parameters of Weibull functions fitted to survival curves based on the estimated ages at death of fossilized remains. Although tyrannosaurs are more closely related to birds than to mammals, they apparently aged at rates similar to mammals of comparable size. Rate of growth in body mass of tyrannosaurs was similar to that of large mammals, and their rates of ageing were consistent with the estimated extrinsic mortality, which is strongly correlated with the rate of ageing across birds and mammals. Thus, tyrannosaurs appear to have had life histories resembling present-day large terrestrial mammals.

Rate of ageing in warm-blooded vertebrates appears to be adjusted in response to extrinsic mortality and potential lifespan, independently of both physiological and developmental rates. However, individuals in species with the slowest rates of ageing suffer the highest proportion of ageing-related mortality, hence potentially strong selection to further postpone senescence. Thus, the longest observed lifespans in birds, tyrannosaurs and mammals might be close to the maximum possible.

Eastmanosteus calliaspis is one of two fossil fish species in which ancient but well-preserved soft tissue has been found. The fossilized muscle cells, blood vessels, and nerve cells shed light on an important group of fish that were the evolutionary precursors of large land animals.

Abstract: In this paper, we show exceptional three-dimensionally preserved fossilized muscle tissues in 380–384Myr old placoderm fish (Late Devonian), offering new morphological evidence supporting the hypothesis that placoderms are the sister group to all other gnathostomes. We describe the oldest soft tissue discovered in gnathostomes, which includes striated muscle fibres, circulatory and nerve tissues, preserved as phosphatized structures precipitated by microbial infilling of small, protected areas under the headshield of the arthrodire, Eastmanosteus calliaspis. Muscle impressions have also been found in the ptyctodontid, Austroptyctodus gardineri. The specimens display primitive vertebrate muscle structures; in particular, shallow W-shaped muscle blocks such as those observed in lampreys. New information from fossilized soft tissues thus elucidates the affinities of the placoderms and provides new insights into the evolution and radiation of gnathostomes.

A U. of Calgary archaeologist has found the first prehistoric evidence of chimpanzee technology, adding credence to the theory that some of humanity's behavioural hallmarks were actually inherited by both humans and great apes from a common ancestor.

Dr. Julio Mercader uncovered stone 'hammers' last year in the Taï rainforest of Africa's Côte D'Ivoire (Ivory Coast) that date back 4,300 years.

"It's not clear whether we hominins invented this kind of stone technology, or whether both humans and the great apes inherited it from a common forebear," says Mercader. "There weren't any farmers living in this region 4,300 years ago, so it is unlikely that chimpanzees picked it up by imitating villagers, like some scientists used to claim."

The stone hammers that the team discovered, essentially irregularly shaped rocks about the size of cantaloupes -- with distinctive patterns of wear -- were used to crack the shells of nuts. The research demonstrates conclusively that the artifacts couldn't have been the result of natural erosion or used by humans. The stones are too large for humans to use easily and they also have the starch residue from several nuts known to be staples in the chimpanzee diet, but not the human diet.

Monday, February 12, 2007

Keenly observing nature in all its forms—from fossil sloths to mockingbirds, primroses to children—Darwin saw that we all are related.Every living thing shares an ancestry, he concluded, and the vast diversity of life on Earth results from processes at work over millions of years and still at work today. Darwin's explanation for this great unfolding of life through time—the theory of evolution by natural selection—transformed our understanding of the living world, much as the ideas of Galileo, Newton and Einstein revolutionized our understanding of the physical universe.

Darwin's theory of evolution by natural selection underlies all modern biology. It enables us to decipher our genes and fight viruses, and to understand Earth's fossil record and rich biodiversity. Simple yet at times controversial, misunderstood and misused for social goals, the theory remains unchallenged as the central concept of biology. Charles Darwin, reluctant revolutionary, profoundly altered our view of the natural world and our place in it.

The greatest dinosaur hunter of the twentieth century was Barnum Brown, who began his career at the American Museum of Natural History in 1897 as an assistant to Henry Fairfield Osborn. Brown traveled all over the world collecting dinosaurs and fossil mammals. Some consider him to be the last of the great dinosaur hunters.

Brown was always impeccably dressed, often wearing a tie and topcoat even in the field. He was a shrewd "horse trader" when it came to wheeling and dealing for fossil specimens. Many of Brown's greatest discoveries, including the first specimens of Tyrannosaurus rex ever found, are displayed in the Museum's Dinosaur Halls.

Abstract: Fragmentary fossils from northwestern Puerto Rico document the existence of crocodyliforms during the Late Oligocene and Early Miocene. The remains are insufficient to establish new named species, but they are inconsistent with any other crocodylian known from the western hemisphere during the Cenozoic, including extant Alligator and Crocodylus.

They are thus consistent with the hypothesis that Crocodylus is a comparatively recent immigrant into the West Indies and suggest that, as with Australasia and Africa, the Antilles hosted an endemic clade of crocodylians during the Tertiary, later replaced by Crocodylus.

The new specimen, a male, is exquisitely preserved and displays the same foliaceous appearance as extant male leaf insects. Clearly, an advanced form of extant angiosperm leaf mimicry had already evolved early in the Eocene.

We infer that this trait was combined with a special behavior, catalepsy or "adaptive stillness," enabling Eophyllium to deceive visually oriented predators. Potential predators reported from the Eocene are birds, early primates, and bats.

This fossil leaf insect bears considerable resemblance to extant individuals in size and cryptic morphology, indicating minimal change in 47 million years. This absence of evolutionary change is an outstanding example of morphological and, probably, behavioral stasis.

In 1667, a classic paleontological paper by Nicolaus Steno was published by the Royal Society, London. His topic, Head of a shark dissected, represented the first such scientific paper to recognise that fossils were the remains of creatures who had died and subsequently had become petrified. Controversy resulted as the same claim had been made in the time of the ancient Greeks, two millennia earlier.

The Eocene-to-Oligocene transition (~33.5 MA) marks a massive extinction of life in both marine and land environments. Scientists believe the drop in temperature was likely due to changes in oceanic currents.

Researchers analyzed oxygen and carbon isotopes in the preserved teeth and bones of primitive fossil horses and a primitive cloven-hoofed mammal called an oreodont. Oxygen isotopes act as thermometers, telling scientists at what temperature they were formed; carbon isotopes act as barometers, revealing relative humidity.

In 1865, Gregor Mendel, who first discovered the laws of genetics, read his first scientific paper to the Brünn Society for the study of Natural Sciences in Moravia (published 1866).

He described his investigations with pea plants. Although he sent 40 reprints of his article to prominent biologists throughout Europe, including Darwin, only one was interested enough to reply.

Most of the reprints, including Darwin’s, were discovered later with the pages uncut, meaning they were never read.

Fortunately, 18 years after Mendel's death, three botanists in three different countries researching the laws of inheritance, in spring 1900, came to realize that Mendel had found them first. Mendel was finally acknowledged as a pioneer in the field which became known as genetics.Info from Today In Science History

Tuesday, February 06, 2007

Mary Douglas Nicol Leakey was in London, England. She meet her future husband, Louis Leakey, when he asked her to illustrate his book, 'Adam’s Ancestors'. Mary and Louis spent from 1935 to 1959 at Olduvai Gorge in the Serengeti Plains of northern Tanzania where they worked to reconstruct many Stone Age cultures dating as far back as 100,000 to two million years ago. They documented stone tools from primitive stone-chopping instruments to multi-purpose hand axes.

In October of 1947, while on Rusinga Island, Mary unearthed a Proconsul africanus skull, the first skull of a fossil ape ever to be found. It was dated to be twenty million years old. An Australopithecus boisei skull was uncovered in 1959. Not long afterwards, a less robust Homo habilis was found. In 1965 the duo uncovered a Homo erectus cranium.

After her husband died in 1972, Mary continued her work at Olduvai and Laetoli. She discovered Homo fossils at Laetoli which were more than 3.75 million years old, fifteen new species and one new genus. From 1978-81 Mary and her staff worked to uncover the Laetoli hominid footprint trail which was left in volcanic ashes 3.6 million years ago.

Image from HERE where you will also find a slightly more colourful account of her life with Louis.

A new analysis of ancient rocks from the eastern shore of Hudson Bay in northern Quebec, Canada now provides shows that CO2 Earth's atmosphere could have sustained surface temperatures above freezing before 3.75 billion years ago.

Previous studies had shown liquid water existed at Earth's surface even though the weak sun should have been unable to warm the planet above freezing conditions. But high concentrations of CO2 or methane could have warmed the planet, according to the research team.

Three fossil enthusiasts recently set out on an 18-hour hunt near the central city of Indore and ended up with more than a hundred dinosaur eggs (some of which are pictured above, apparently arranged for photographers), the Hindustan Times reported today.

These particular sauropod eggs were found in clusters of six to eight, one of the discoverers told the Hindustan Times. The eggs were laid during the Cretaceous period, roughly 146 to 66 million years ago, by dinosaurs between 40 and 90 feet (12 and 27 meters) long, he added.

Along with the eggs, the fossil hunters uncovered fossilized footprints of the dinosaurs, which used to come from miles around to make their nests in the sandy shores of a long-gone waterway.

Monday, February 05, 2007

Brongniart was a French mineralogist, geologist, and naturalist, who first arranged the geologic formations of the Tertiary Period (from 66.4 to 1.6 million years ago) in chronological order and described them.

He made the first systematic study of trilobites that became important in determining the chronology of Paleozoic strata (from 540 to 245 million years ago).

He helped introduce the principle of geologic dating by the identification of distinctive fossils found in each stratum and noted that the Paris formations had been created under alternate freshwater and saltwater conditions. image.

Sunday, February 04, 2007

The artist Dave Cockrum passed away late last year. This illo of his from an old 1975 issue of "Monsters Unleashed" of one of the more famous fictional Devonian critters is a belated tip of the hat to him.

I was prompted to post this thanks to our friends over at the *new* Atomic Surgery blog who have posted an old Mechanix Illustrated article on how The Creature's costume was created.

Saturday, February 03, 2007

Abstract: We describe the tenth skeletal specimen of the Upper Jurassic Archaeopterygidae. The almost complete and well-preserved skeleton is assigned to Archaeopteryx siemensii Dames, 1897 and provides significant new information on the osteology of the Archaeopterygidae.

As is evident from the new specimen, the palatine of Archaeopteryx was tetraradiate as in non-avian theropods, and not triradiate as in other avians. Also with respect to the position of the ectopterygoid, the data obtained from the new specimen lead to a revision of a previous reconstruction of the palate of Archaeopteryx.

The morphology of the coracoid and that of the proximal tarsals is, for the first time, clearly visible in the new specimen. The new specimen demonstrates the presence of a hyperextendible second toe in Archaeopteryx. This feature is otherwise known only from the basal avian Rahonavis and deinonychosaurs (Dromaeosauridae and Troodontidae), and its presence in Archaeopteryx provides additional evidence for a close relationship between deinonychosaurs and avians.

The new specimen also shows that the first toe of Archaeopteryx was not fully reversed but spread medially, supporting previous assumptions that Archaeopteryx was only facultatively arboreal.

Finally, we comment on the taxonomic composition of the Archaeopterygidae and conclude that Archaeopteryx bavarica Wellnhofer, 1993 is likely to be a junior synonym of A. siemensii, and Wellnhoferia grandis Elżanowski, 2001 a junior synonym of A. lithographica von Meyer, 1861.

Mantell, a physician of Lewes in Sussex in southern England, had for years been collecting fossils in the sandstone of Tilgate forest, and he had discovered bones belonging to three extinct species: a giant crocodile, a plesiosaur, and Buckland's Megalosaurus. But in 1822 he found several teeth that "possessed characters so remarkable" that they had to have come from a fourth and distinct species of Saurian. After consulting numerous experts, Mantell finally recognized that the teeth bore an uncanny resemblance to the teeth of the living iguana, except that they were twenty times larger. In this paper, the second published description of a dinosaur, he concluded that he had found the teeth of a giant lizard, which he named Iguanodon, or "Iguana-tooth."

Mantell illustrated his announcement with a single lithographed plate. Mantell included at the bottom of the plate a drawing of a recent iguana jaw, which is shown four times natural size, and for further comparison, he added views of the inner and outer surface of a single iguana tooth, "greatly magnified."

The traditional story that Mantell's wife found the first teeth in 1822, while the doctor was visiting a patient, appears, alas, to be unfounded.

“Both coasts were very close and the basins between them could emerge occasionally,” said study leader Fernando Escaso of the Autonomous University of Madrid, Spain.

The scientists unearthed the new Stegosaurus fossils, which included a tooth and parts of the animal’s spinal column and leg bones, near the city of Batalha, in central Portugal. Preliminary analyses show the fossils to be indistinguishable from a species previously found only in North America, called Stegosaurus ungulatus.

The only other dinosaur for which bones have been found in both North America and Europe is a species of Allosaurus.

Abstract: More than one century after its original description by Marsh in 1877, we report in this paper the first uncontroversial evidence of a member of the genus Stegosaurus out of North America. The specimen consists of a partial skeleton from the Upper Jurassic of Portugal, herein considered as Stegosaurus cf. ungulatus. The presence of this plated dinosaur in the upper Kimmeridgian–lower Tithonian Portuguese record and synchronic levels of the Morrison Formation of North America reinforces previous hypothesis of a close relationship between these two areas during the Late Jurassic. This relationship is also supported by geotectonic evidences indicating high probability of an episodic corridor between the Newfoundland and Iberian landmasses. Together, Portuguese Stegosaurus discovery and geotectonic inferences could provide a scenario with episodical faunal contact among North Atlantic landmasses during the uppermost Kimmeridgian–lowermost Tithonian (ca. 148–153 Ma ago).

Abstract [edit]: The orientation of the scapulocoracoid in sauropod dinosaurs is reconstructed based on comparative anatomical investigations of pectoral girdles of extant amniotes. In the reconstruction proposed here, the scapula of sauropods stands at an angle of at least 55° to the horizontal plane in mechanical coherence with the sternal apparatus including the coracoids. The coracoids are oriented cranioventrally to the rib cage and the glenoid is directed mediolaterally, which allows the humerus to swing in a sagittal plane.

Reconstruction of the pectoral girdle of Camarasaurus.

The inclination of the scapula to the horizontal plane is reconstructed for Diplodocus (60-65°), Camarasaurus (60-65°), and Opisthocoelicaudia (55-65°). The inclination of the scapulocoracoid has consequences for the overall body posture in Camarasaurus and Opisthocoelicaudia, where the dorsal contour would have ventrally declined toward the sacrum.

It's a mystery why the speed and complexity of evolution appear to increase with time. For example, the fossil record indicates that single-celled life first appeared about 3.5 billion years ago, and it then took about 2.5 billion more years for multi-cellular life to evolve. That leaves just a billion years or so for the evolution of the diverse menagerie of plants, mammals, insects, birds and other species that populate the earth.

Scientists now suggest a possible answer; the speed of evolution has increased over time because bacteria and viruses constantly exchange transposable chunks of DNA between species, thus making it possible for life forms to evolve faster than they would if they relied only on sexual selection or random genetic mutations.

Horizontal gene transfer (HGT) is a cross-species form of genetic transfer. It occurs when the DNA from one species is introduced into another. The idea was ridiculed when first proposed more than 50 years ago, but the advent of drug-resistant bacteria and subsequent discoveries, including the identification of a specialized protein that bacteria use to swap genes, has led to wide acceptance in recent years.

In comparison to existing models that account for only point mutations or sexual recombination, the new model shows how HGT increases the rate of evolution by propagating favorable mutations across populations.